A device comprising a plurality of hollow units (11), each unit comprising a circumferential wall (12) having a first end region (5) and a second end region (13), wherein the first end region is narrower than the second end region and the plurality of units are in an interconnected arrangement, such that the first end region of a first unit (14) of the plurality of units is received within the second end region of a second unit (15) of the plurality of units, and a flexible elongate member (3) extends longitudinally through the interconnected units, whereby the circumferential walls of the interconnected first and second units abut each other and the interconnected units are secured together.